Type (s) fuse automation

ABSTRACT

THE PRESENT INVENTION RELATES TO PLUG FUSES REFERRED TO IN THE WIRING DEVICE FIELD AS OF A &#34;TYPE S&#34; OR EDISON BASE VARIETIES AND TO IMPROVEMENTS IN THE MANUFACTURE OF THESE FUSES. MORE SPECIFICALLY IT RELATES TO SUCH FUSES IN WHICH MANUFACTURING MAY BE ACCOMPLISHED WITH AUTOMATIC EQUIPMENT AND FOR WHICH THE STRUCTURE OF THE FUSES INCLUDES AN ALIGNMENT OF THE FUSE LINK MOSTLY PARALLEL TO THE AXIAL DIRECTION IN THE FUSE AND WHICH PERMITS A RELIABLE PARALLEL ENTRY OF A TOOL OR OTHER ARTICLE INTO THE FULL DEPTH OF THE PLUG FUSE.

D66 12, Q G|| ETT TYPE (S) FUSE AUTOMATION z sheets-sheet 1 Filed Abril 30, 1971 Fl G. 7

Doa. ll2, 1972 G|| ETT 3,706,063

TYPE (vs) FUSE AUTOMATION Filed Abril 30, 19?1` 2 Sheets-Sheet 2 FIG@ 'nited States Patent Oice 3,706,063 TYPE (S) FUSE AUTOMATION Colin Gillett, East Greenwich, RJ., assignor to General Electric Company Filed Apr. 30, 1971, Ser. No. 138,987 Int. Cl. H01h 85/10, 85/20, 85/62 U.S. Cl. 337-262 1 Claim ABSTRACT OF TI-IE DISCLOSURE ble parallel entry of a tool or other article into the full depth of the plug fuse.

The present invention relates to improved manufacture of plug fuses and particularly to plug fuse construction which facilitates manufacture with automated equipment. Conventional plug fuses have been manufactured for many lears with a window at one end for viewing a fuse link within the fuse body. The particular shape and contour of the link has for the most part been designed to maximize the visibility of the portion of the link which will be blown when an excess power surge passes through the fuse and various forms of such links are taught in the art including those taught for example in such patents as 2,688,061; 2,527,160; 3,089,012; 2,557,926; and 3,042,777.

It will be apparent from a review of these and other patents as well as plug fuse structures formed heretofore that the fuse link is arrayed within the plug fuse body in such manner that a portion of the link will lie across the cavity within the fuse body and may lie generally parallel to the surface of the window or will in any event stretch across the width of a cavity as for example in the manner taught in Pat. 3,042,777 so that a high visibility of the link and various portions thereof is effected.

In this particular patent there is an accessory in the form of a weight mounted onto a portion of the link displayed beneath the window of the fuse and the weight serves in parts to induce a greater probability of movement of a severed portion of the link after excessive power passes through the link. Because of the array and alignment of various portions of the link in the fuse chamber it has not been feasible heretofore to manufacture fuses on automated equipment because it was not possible to introduce adequate tooling or parts into the chamber and to permit the tooling or parts to accomplish their assigned tasks by movement all the way to the lower portion of the chamber for a positioning of the lower end of the link or the soldering or otherwise attaching the lower end of the link to the lower contact of the plug fuse. Further, it has not been feasible heretofore to produce a fuse which did not have the segment of the fuse stretched across beneath the window in high visibility fashion or otherwise arrayed at least in part to intersect the central axis of the plug to permit the user to determines whether the fuse were or were not blown.

It is accordingly one object of the present invention to provide a fuse structure having novel alignment of fuse link.

Another object of the present invention is to provide a fuse structure having a link which permits` ready visability 7 although the link does not extend across the fuse chamber beneath the window.

3,706,063 Patented Dec. l2, 1972 A further object of the present invention is to facilitate manufacture of fuses in automated equipment.

Still another object is to provide a mechanism for automatic manufacture of plug fuses.

Other objects will be in part apparent and in part pointed out in the description which follows.

In one of its broader aspects the objects of the present invention are achieved by providing a plug fuse having a generally cylindrical insulating housing, an axially located electrical contact at one end and a covered window for viewing the housing interior at the other, a side contact extending through the sidewall of said housing, a fuse link in the interior chamber of said housing extending between the axial contact and the side contact, said link having in general an inverted l' form the longer arm of the I form resting in the central contact and the shorter ams of the l form resting in a side well in stable fashion the loop of the I arching over an interior side wall portion at least partially defining said side well.

The manner of carrying the invention into effect and the article produced will be understood with greater clarity by reference to the accompanying drawing in which:

FIG. 1 is a top plan view of a fuse of the present invention.

FIG. 2 is an elevational view of a type S fuse as seen in FIG. 1.

FIG. 3 is an axial section of a Lfuse article taken along a line 3 3 of FIG. 1 with the fuse cover omitted.

FIG. 4 is a vertical section similar to that of FIG. 3 but where the product illustrated is an Edison base plug fuse rather than the type S fuse of FIGS. l and 2.

FIG. 5 is a top plan view of a fuse link such as that used in the present invention.

FIG. 6 is a sectional view of the link of FIG. 5 taken along the line 6-6 of FIG. 5.

FIG. 7 is a link as shown in FIG. 5 but omitting the heat sink element.

FIG. -8 is a sectional view similar to that of FIG. 3 but illustrating a link poised.

FIG. 9 is a sectional view similar to that of FIG. 3 but illustrating a link without the heat sink of FIG. 3.

FIG. 10 is a sectional view similar to that of FIG. 4 but illustrating a different form of link prior to soldering in place.

Referring now first to FIGS. 1 and 2 there is seen a top plan view and a side elevation respectively of a finished fuse product of the type S configuration including a porcelain insulating body 20 having a threaded lower portion 24 and a ilanged upper portion 23.

A Window 12 is held on the upper end by metal cap 14 and a set of contacts 26 and 28 provide external connections for an internal fuse link 10 seen through the window of FIG. l.

A more detailed description is now given of such a product referring next to FIG. 3. Starting at the bottom a contact 26 provides one external electrical contact of the fuse product. 'Ihe contact is in the form of an eyelet inserted through an opening in the bottom of the porcelain body. The upper end of eyelet 26 has a well 30 the upper walls of which are expressed and bowed out after insertion of the eyelet to secure the eyelet in place.

A body 34. of low melting metal is shown in place in the well embedding the tip 36 of one end sector of a fuse link. The fuse link may have a number of sectors and at least one sector of reduced cross-section located below the window 12 within easy view through the window.

A second body 43 of low melting metal secures the 0 upper end of fuse link in an upper side well 45. The fuse The form of the fuse link within the fuse chamber 32 is in certain respects important and in other respects not so important.

What is important is that the link have a form prior to assembly which permits it to be placed into a fuse body and to be held in place in the fuse body during subsequent assembly and fabrication steps.

What can also be important is that the link should be capable of lying predominantly along the side or sides of chamber 32 to a degree which makes possible entry of a tool such as 70 into the full depth of the fuse including well 30. The importance of the tool entry depends on the mode of fuse assembly employed.

|What is less important is that the link have a particular array of sectors of reduced or increased cross-section or the like.

In the illustrative example given the lower end 36 of the fuse link is secured by means of a body of low melting metal. Accordingly, a tool such as tool 70 shown in FIG. 3 is preferably a heating tool and may be an internal resistance heater or inductance heater or similar V suitable heating tool.

The tool need not be introduced along the axis of the plug fuse cylinder or of the internal longitudinal axis of the chamber within the housing but may be introduced along a path set at an angle to the axis.

It is evident for example depending on the shape and size of the tool that some difliculty may be encountered in fitting the tool and link end 36 into the well 30 in such manner as to facilitate fusing the metal 34 and embedding or otherwise lixing the end 36 in place in secure electrical contact with contact 26.

In other words what is important where tools are to be employed in the assembly is that the fuse structure include a clear path large enough for a tool and extending from the top opening of the fuse housing all the way into the region where the link is to be aillxed to the center contact 26.

The orientation of the path relative to the link or to the chamber wall is secondary to the orientation of link and wall to provide the tool path essentially all the way down to where the attachment of link to contact is made.

It is noteworthy that regardless of the manner in which the attachment of link and to contact is made the assembly is automatable in part because the inverted J form of link is held stably in position in the fuse body once it is placed there as, for example, in the manner illustrated in FIG. 8.

The article resulting from gravity retention of a link the inverted J form in a fuse body as for example the article of FIG. 8 with the link resting by gravity in both internal wells is itself unique. In addition it permits unique automatic assembly as illustrated by the tool insertion of FIG. 3. Referring once again to FIG. 3 tool 70 will be seen to halve a tapered lower end 72 and this can facilitate delivering heat to a fusible metal in well 30 so as to embed fuse end 36 into body 34. Because of this taper and because the tool is offset from the central axis of chamber 32, the tapered end of tip 72 can fuse the metal body and leave fuse link end 36 positioned and secured generally centrally in cup 30 by fused metal body 34. 4

Where a heat sink such as 40 is crimped onto one of the broader sectors of the link, as between a thinner sector 39 and a still thinner sector- 42, the limit of available room in the chamber 32 for tool and link manipulation may make advisable use of a fairly narrow tool 70` and/ or a closer spacing of the link against the inner side wall of chamber 32. In this arrangement the entire link may be disposed between the central axis and the side wall. It will be evident from FIG. 3 that the link has this essentially one side alignment. With this combination of heat sink 40 pressed at least partially against the wall of chamber 32 an upper broader portion 74 of tool 70 can descent far enough to bring the narrowed tip of tapered end 72 of tool 70 into well 30 without dislodging the link from its position in chamber 32 and without fusing or damaging the fuse link itself.

The fuse link actually has several segments as illustrated in FIG. 5. Starting at the sector 38 which is atlixed within well 30 there is the end tip 3'6 of the sector which is embedded in solder in the version shown in FIG. 3. Moving further away from the lower end as seen in FIG. 3 there is the thin sector 33 of shorter length and the thinner and longer sector 42. Between these two is the lbroader sector 41 and in the form shown in FIGS. 3, 5, and 6 there is crimped on this broader sector the heat sink 40. Heat sink 40 lgives to the link a time delay performance characteristic well known in the art.

Sector 44 at the opposite end of the link is the sector embedded in the side wall contact well or pocket 45.

The link as shown in FIGS. 5 and 6 in a form similar to that described in copending application Ser. No. 138,- 989 tiled Apr. 30, i1971, assigned to the assignee of the subject application and tiled simultaneously herewith.

However, the link need not have the form shown in the illustration of FIG. 3. Alternative forms are contemplated within the scope of the present invention. An alternative form is illustrated in FIG. 4 and as will be evident in that figure the heat sink 40 is absent and the form of link used is the simpler link form of FIG. 7. Further, fuse links may have alternative configurations within the generalized form of the inverted J. The upper loop may ascend to different heights above the barrier rim 29 and the path of the longer leg may follow more or less closely the internal contour of the walls of chamber 32, all without departing from the general form of the inverted J.

FIG. 4 shows a plug fuse similar in many respects to the fuse of FIG. 3 and having many similar parts performing essentially the same function as performed by parts having common numbers in FIG. 3. In other words the F-IG. 4 has some parts bearing the same numbers as parts of FIG. 3. Where the numbering is the same, the function performed by the part is essentially the same. The main ditferences relate to the different fuse link and this bears different numbers than the link of FIG. 4.

With reference to FIGS. 4 and 7 the pertinent portions of the link are as follows. The lower end 58 is embedded at its tip 59 in the solder 34 in well 30. Above this lower sector 58 is a thinner sector 56. A mid-sector 54 is free of the crimped heat sink such as is used on the link of the fuses of FIGS. 3 and 5.

Above the mid-sector 54 is narrower sector 52 which is the longest of the narrow sectors and accordingly the one most likely to blow. This sector corresponds to sector 42 of the link illustrated in FIGS. 5 and 3. The other end sector 50 corresponds to sector 44 as seen in FIGS. 5 and 3 and is itself embedded in a solder-like metal body in pocket .45 in essentially the same manner in which sector 44 is embedded in solder in pocket 45 of the device illustrated in FIG. 3.

The different form of fuse link and other parts, and the diferent part alignment in the -device of FIG. 3 as compared to the device of FIG. 4 is in part a difference which results from elimination of the crimped on heat sink 40 of FIG. 3, and in part the result of the change in fuse housing and particularly the threads and external contacts 28 and 1 28 of the respective fuse devices.

But there are other forms of device and other forms of fuse link contemplated within the scope of the present invention which go beyond the alternative or varied forms shown in FIGS. 3 through 7 respectively.

One such alternative article is that shown in FIG. l0. In this figure a fuse link such as that of FIG. 5 is bent into an inverted I form with a stepped longer leg bearing a heat sink crimped onto the leg. As seen it rests by gravity at each end in the respective wells 30 and 45. Also present with each of the fuse ends 36 and 44 are the bodies 71 and 73 of fusible metal. Heating of these What is claimed is: 1. A fuse comprising an insulating fuse body divided internally by a side wall barrier into a main chamber having a bottom well and a side Well chamber,

said body having an external axial lower contact and an external perimeter upper contact,

said contacts communicating through the insulating Walls of said body with an internal axial bottom well and an upper side well respectively,

a fuse link extending between said wells,

said fuse link having a general J configuration,

the longer leg of said J extending into the bottom well of said fuse body,

the shorter leg extending into the side well of said body,

the longer leg being aligned mostly parallel to the axial direction of the fuse body but spaced from the axis,

the longer leg having a length substantially greater than the distance from the bottom well to the upper edge of said barrier,

the most fusible sector of the fuse link being at the bottom of the I,

the bottom of the J being arched over and out of thermal contact with the upper edge of said barrier,

and the ends of said fuse link being soldered in said wells to ths respective contacts.

References Cited UNITED STATES PATENTS 920,005 4/ 1909 Badeau et al. 337-255 1,385,285 7/19211 Thomas 337-260 2,068,584 1/ 1937 Wood 337-265 3,042,777 1/\1962 Pertici 337-26()l XR 3,111,568 11/1963` Robinson 337-268 XR ROY N. ENVALL, IR., kPrimary Examiner U.S. Cl. X.R. 

